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. 2023 Aug 7;9(5):2150–2159. doi: 10.1002/vms3.1237

Growth performance and physiological responses of broilers fed Stylosanthes hamata leaf meal in a hot tropical environment

Adewale E Adejuyigbe 1, Olajide M Sogunle 2, Okanlawon M Onagbesan 1, Oyegunle E Oke 1,3,✉
PMCID: PMC10508513  PMID: 37549043

Abstract

Background

Forage plants are considered an essential source of vitamins, protein and energy and could decrease the intake of the conventional diets by up to 10% if young quality forage plants are offered and about 7% of a broiler's daily protein needs and 3% of their daily calorie needs can be met by pasture. However, there is a paucity of data on the quantification of the herbage intake in broiler chickens.

Objectives

This trial was designed to determine the performance and physiological response of broilers fed diets containing Stylosanthes hamata leaf meal (SHLM) at 0%, 1%, 5%, 10%, 15% and 20% inclusion (weight for weight) in a basal diet of poultry.

Methods

Two hundred and forty‐day‐old Arbor Acres broiler chicks were used for this trial. They were allocated at random to each of the 6 dietary treatment groups with 4 replicates of 10 chickens each. The study lasted for 35 days, during which data were collected weekly.

Results

Results indicated no difference (p > 0.05) in body weight gain, feed consumption and feed conversion ratio of broiler chickens across all ages. Although the plasma triiodothyronine (T3) concentration of the birds was influenced at the sixth week of age, there was no consistency in the trend. At the eighth week of age, chickens on 15% SHLM had significantly (p < 0.05) higher cortisol (3.22 ng/mL) concentrations compared to 10% (3.13 ng/mL) and 20% (3.16 ng/mL) SHLM treatment groups. Treatment groups, regardless of the age of the chickens, had similar (p > 0.05) mean plasma creatinine values.

Conclusions

The study concluded that SHLM could be incorporated into broiler feed up to 20% without a deleterious impact on physiology and performance indices.

Keywords: chickens, forage, growth, physiology, tolerance

Leguminous plants could be a vital source of vitamins, protein and energy and may reduce the dependence on conventional feedstuff. This study investigated the effects of different inclusion levels of Stylosanthes hamata leaf meal on broiler chickens. It was concluded that up to 20% inclusion of the meal did not adversely affect the performance of broiler chickens.

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1. INTRODUCTION

The animal protein consumed in developing nations is still much lower than the expected threshold (Vries‐ten Have et al., 2020). As with many other developing nations, Nigeria has a protein shortfall, especially regarding high‐quality animal protein. Increased attempts are being made to increase the productivity of traditional livestock, including cattle, sheep, goats and chickens, due to the insufficient supply of protein they provide (Iheukwumere, 2008). Various attempts have been made to bridge this gap, notably among them is the expansion of commercial poultry production, which has a great deal of potential to close the protein gap as quickly as possible (Kpomasse et al., 2021; Oke et al., 2021). However, the cost of feeding has remained an important constraint for sustainable chicken production. Feed, which has always been a major limiting factor in the growth of the poultry industry, accounts for over 70% of the total cost of producing poultry (Willems et al., 2013). Concerted efforts are needed in utilizing locally available and cheap ingredients to cut down the birds’ production costs. The inclusion of leguminous forage leaves in chickens’ diets can be explored as a less costly and suitable protein source (Agbede & Aletor, 2003).

Incorporating pasture foliage leaves may provide a source of protein and energy for birds. Additionally, various bioactive substances, including xanthophylls and anticancer and hypocholesterolemic substances, are present in the forage leaves, which may increase the quality of chickens’ meat (Ponte et al., 2004). Poultry birds raised on pasture have better quality meat because of the substantial increase in the nutritional composition of pastured poultry, especially in omega‐3 fatty acids. Consumption of meat high in omega‐3 fatty acids helps in the reduction of the incidence of degenerative disease, for instance, heart disease, strokes and cancer (Ponte et al., 2008). A substantial consumption of herbage has been recorded in chickens foraging on different forage plants (Rivera‐Ferre et al., 2007). According to the authors, birds might get up to 7% and 3% of their daily protein and energy needs, or 0.39 g of nitrogen and 62.9 kJ metabolizable energy (ME), respectively, from the forage. In addition, Buchanan et al. (2007) suggested that chickens have the capacity to use the amino acids present in forages and to derive little amounts of energy from forage plants in relation to forage digestibility. A novel way to manipulate the amount of some micronutrients in chicken feed to increase consumer nutrient intake or enhance their general health is to include pasture species. It has been demonstrated that forage plants could supply up to 7% of daily protein and 3% energy requirements of broilers (Rivera‐Ferre et al., 2007), but none has recommended a particular pasture or herbage intake and its specific importance on chickens (Ponte et al., 2008). Using legumes, such as Stylosanthes hamata, in the diets of chickens may help reduce the over‐dependence on conventional feedstuffs. S. hamata contains crude protein and ME of 15.07% and 8.41 MJ/kg DM, respectively (Kumar et al., 2020).

Furthermore, the increasing understanding of polyunsaturated fatty acids’ physiological functions and the health advantages of regular consumption have spurred awareness in the dietary sources of such nutrients from plant sources (Howe et al., 2006). Studies have revealed that the supplementation of pasture species in the diet of birds enhanced their performance (Oke et al., 2015, 2014; Oke et al., 2021; Yannakopoulos et al., 2005).

It is believed that pastures are excellent suppliers of bioactive substances and alpha linolenic acid. The composition of a wide variety of bioactive constituents in the legume plants, including anticarcinogenic and hypocholesterolemic chemicals and xanthophylls, could improve the quality of poultry meat and serve as a source of energy and protein in chickens (Ponte et al., 2008). However, there is a scarcity of data on the dietary supplementation of leguminous leaves, particularly S. hamata, on broiler chickens. Our earlier study (Oke et al., 2015) indicated that birds raised on S. hamata pasture had a better performance than those raised on grass pasture. However, we still need to quantify the daily herbage intake. The present trial sought to evaluate the influence of S. hamata supplementations in the diet of broilers to establish appropriate levels the birds could tolerate without adverse effects on their productivity.

2. MATERIALS AND METHODS

2.1. Processing of Stylosanthes hamata leaf

Fresh S. hamata leaves were harvested at the Research Farm before the flowering stage. The branches were threshed carefully to separate the leaves from the twigs. The leaves were air‐dried until crispy to the touch before milling to obtain dried S. hamata leaf meal (SHLM). The chemical composition of SHLM was determined using the description of Pearson (1976). The crude protein, crude fibre, ash and ether extract were 16.72%, 3.2%, 1.10% and 0.34%, respectively.

2.2. Experimental birds and management

A total number of 240 day‐old Arbor Acres broiler chickens were obtained from a reputable hatchery (Obasanjo Farms Nigeria Limited). The chickens were raised intensively on deep litter floor pens covered with wood shavings. About 8–10 cm depth of wood shavings was used as bedding prior to stocking; the pens were properly cleaned and disinfected.

Birds were housed under six experimental feeding groups of a basal diet (Table 1) with different levels of S. hamata, namely 0%, 1%, 5%, 10%, 15% and 20% inclusion levels. At the beginning of the experiment, birds were individually weighed and randomly distributed into six experimental groups. Four replicates of 10 birds (a total of 40 birds per treatment) were used for each of the experimental groups. Water and feed were provided ad libitum.

TABLE 1.

Experimental diet composition.

Starter diet Finisher diet
Ingredient 0 1.00 5.00 10.00 15.00 20.00 0.00 1.00 5.00 10.00 15.00 20.00
Maize 53.2 52.67 50.54 47.88 45.22 42.56 59.00 58.41 56.05 53.10 50.15 47.20
Soya beans 32 31.68 30.40 28.80 27.20 25.60 23.50 23.27 22.33 21.15 19.98 18.80
GNC 4.7 4.65 4.47 4.23 4.00 3.76 5.50 5.45 5.23 4.95 4.68 4.40
WO 4.5 4.46 4.28 4.05 3.83 3.60 6.50 6.44 6.18 5.85 5.53 5.20
Stylosanthes 0 1.00 5.00 10.00 15.00 20.00 0.00 1.00 5.00 10.00 15.00 20.00
FM 2 1.98 1.90 1.80 1.70 1.60 2.00 1.98 1.90 1.80 1.70 1.60
BM 2.5 2.48 2.38 2.25 2.13 2.00 2.30 2.28 2.19 2.07 1.96 1.84
OS 0.5 0.50 0.48 0.45 0.43 0.40 0.70 0.69 0.67 0.63 0.60 0.56
Meth 0.1 0.10 0.10 0.09 0.09 0.08 0.10 0.10 0.10 0.09 0.09 0.08
a Premix 0.25 0.25 0.24 0.23 0.21 0.20 0.20 0.20 0.19 0.18 0.17 0.16
salt 0.25 0.25 0.24 0.23 0.21 0.20 0.20 0.20 0.19 0.18 0.17 0.16
Total 100 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00
Calculated
CP 23.3 23.25 22.98 22.65 22.32 21.99 18.46 18.44 18.37 18.28 18.19 18.11
ME 3051 3040.35 2998.72 2946.69 2894.65 2842.62 2937.65 2928.37 2891.27 2844.89 2798.51 2752.13
CF 3.3 3.30 3.30 3.29 3.29 3.28 3.20 3.20 3.20 3.20 3.20 3.20
ASH 0 0.01 0.06 0.11 0.17 0.22 0.00 0.01 0.06 0.11 0.17 0.22
EE 3.78 3.74 3.61 3.43 3.26 3.09 3.83 3.80 3.66 3.48 3.31 3.13
Calcium 1.26 1.40 1.92 2.57 3.23 3.89 1.25 1.38 1.91 2.56 3.22 3.88
Phosphorus 0.79 0.80 0.84 0.88 0.93 0.98 0.74 0.75 0.79 0.83 0.88 0.93
Lysine 1.18 1.21 1.34 1.51 1.68 1.84 0.98 1.02 1.16 1.33 1.51 1.69
Methionine 0.42 0.43 0.47 0.50 0.54 0.58 0.39 0.40 0.43 0.47 0.52 0.55
Met + Cys 0.77 0.77 0.79 0.81 0.84 0.85 0.70 0.71 0.73 0.75 0.78 0.80
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Abbreviations: BM, bone meal; CF, crude fibre; CP, crude protein; EE, ether extract; FM, fish meal; GNC, Groundnut cake; ME, metabolizable energy; OS, oyster shell; WO, wheat offal.

a

Provided% of diet – vitamin A (12,000 IU): vitamin D3 (2500 IU), vitamin E (30,000 IU), vitamin K3 (2000 mg), vitamin B2 – riboflavin (3 mg), vitamin B3 – nicotinic acid (10 mg), vitamin B5 (15 mcg), pantothenic acid (15,000 mg), manganese (80,000 mg), selenium (0.1 mg), folic acid (1500 mg), biotin (50 mcg), chlorine chloride (300,000 mg).

The experiment lasted for 35 days (56 days of age). SHLM inclusion in the diet was introduced on day 21. Drinkers and feeders were cleaned, and litter materials were changed as when due. Sanitation of the environment was maintained throughout the experimental period. The experimental diet is shown in Table 1.

2.3. Data collection

2.3.1. Growth performance

Weight gain

The weight of birds was recorded weekly using a digital sensitive weighing scale. Weight gain was calculated as the difference between the final weight and the initial weight.

2.3.2. Feed intake per bird

The feed intake was recorded weekly. Feed intake was calculated by using the following formula:

Feedintakeperbirdg=feedsupplied−feedleftoversnumberofbirds

2.3.3. Feed conversion ratio (FCR)

The feed conversion ratio (FCR) was calculated as

Feedconversionratio=totalfeedintaketotalbodyweightgain

2.3.4. Determination of biochemical and haematological parameters

Eight chickens per treatment group were selected at random and blood samples were collected for analysis (haematological and biochemical parameters) at the starter (3 weeks of age) and finisher phases of the experiment. Blood samples were obtained from the birds through their brachial veins using clean and sterile 5 mL hypodermic needle syringes. Five millimetres (5 mL) of blood was collected into labelled sample bottles without ethylenediaminetetraacetate (EDTA), and another 5 mL was collected into EDTA bottles.

2.4. Haematological analyses

2.4.1. Packed cell volume

The microhaematocrit method was used, as described by Dacie and Lewis (1995). The capillary tubes were filled with the fresh anticoagulated blood sample at about three quarters of its length after being mixed. Filled tubes were spun in a microhaematocrit centrifuge for 5 min at 11,000 rates per minute (rpm). The fractional lengths of packed cells and blood were read, and the corresponding packed cell volume (PCV) values were read out on the microhaematocrit reader.

2.4.2. Red blood cell (RBC)

Small amount of anticoagulated fresh blood sample was accurately diluted (1:200) with a fluid (0.9% NaCl) and mixed well. The diluted blood was then mounted on a haemocytometer, and the number of erythrocytes in a circumscribed volume (0.02 mm3) was counted microscopically.

2.4.3. Haemoglobin concentration (Hb)

This was determined colourimetrically using a spectrophotometer (model SP6‐450 UV, Pye Unicam).

2.4.4. White blood cell (WBC) count

The total white blood cells (WBCs) were determined immediately after anticoagulated blood collection with the use of a Neubauer haemacytometer counting chamber and the WBCs were separated. The blood samples were pipetted and then mixed with 5 mL of WBC diluting fluid. The sample was then put into a haemocytometer, and the cells were counted and expressed as 109 WBC per litre of blood.

The mean corpuscular haemoglobin (MCH), MCH concentration and mean cell volume were estimated from haemoglobin concentration, red blood cell (RBC) and PCV.

2.5. Plasma cortisol and triiodothyronine determination

The blood samples collected into EDTA bottles were centrifuged immediately at 2000 × g, at 4°C for 15 min for plasma harvest. Plasma cortisol and triiodothyronine levels were determined using commercial diagnostic ELISA kits (DiaMetra). Plasma cortisol and triiodothyronine concentrations were determined at weeks 4–7 and 8 of age.

2.6. Serum creatinine

The blood samples collected into the bottles without EDTA were also centrifuged to separate the serum. The serum creatinine was analysed weekly from day 28 onwards. Serum creatinine was determined using the colourimetric method. The supernatant was drained off after centrifuging 1.0 mL of trichloroacetic acid and 1.0 mL of serum at 250 rpm for 10 min. At a temperature of 250°C, the mixture was allowed to stand for 20 min. In comparison to the blank, the sample's and standard's absorbance was measured.

2.7. Carcass traits

Two birds per replicate were randomly picked for slaughtering to evaluate carcass traits at the end of the eighth week of the experiment. The live weights of the birds were taken before slaughtering. Following slaughter, the birds were scalded, de‐feathered and cut into retail parts. The obtained values were expressed as relative weights. Parameters determined were liveweight, drumsticks, breast, thighs, wings, shank, gastrointestinal tract (GIT) length, gizzard, whole GIT, liver, heart, spleen and abdominal fat.

2.8. Statistical design and analysis

Data obtained throughout the study were subjected to a one‐way analysis of variance using SAS (2007) statistical software package. Significant means were separated using Tukey's HSD test of the same statistical software package.

3. RESULTS

3.1. Growth performance

The effect of the diet on the growth performance characteristics of the birds between 3 and 8 weeks of age is shown in Table 2. The data obtained revealed that SHLM inclusion in the basal diet had no significant (p > 0.05) influence on FCR, feed intake, final live weight and weight gain of broiler chickens across all ages among the treatments.

TABLE 2.

Growth performance of broilers fed diet containing Stylosanthes hamata leaf meal.

S. hamata leaf meal
Parameter Week 0% 1% 5% 10% 15% 20% SEM p Value
Initial weight (g) 4 767.50 777.50 765.0 770.0 780.0 775.00 24.889 0.946
Feed intake (g) 5 825.00 860.00 822.50 830.00 842.50 832.50 14.658 0.9858
6 940.00 942.50 935.00 950.00 945.00 937.50 12.228 0.9996
7 1072.50 1082.50 1100.00 1062.50 1085.00 1090.0 17.067 0.9946
8 1227.50 1265.00 1235.00 1220.00 1237.50 1217.50 16.614 0.9787
Body weight (g) 5 1202.50 1227.50 1210.00 1207.50 1220.00 1217.50 8.273 0.9712
6 1655.00 1652.50 1647.50 1640.00 1632.50 1647.50 7.171 0.9648
7 2405.00 2392.50 2390.00 2387.50 2385.00 2402.50 7.936 0.9793
8 2830.00 2815.00 2835.00 2820.00 2822.50 2825.00 8.297 0.9910
Body weight gain (g) 5 435.00 450.00 445.00 437.50 440.00 442.50 7.3885 0.9959
6 452.50 425.00 437.50 432.50 412.50 430.00 9.0423 0.9030
7 750.00 740.00 742.50 747.50 752.50 755.00 8.4694 0.9970
8 425.00 422.50 445.00 432.50 437.50 422.50 7.9609 0.9658
Feed conversion ratio 5 1.89 1.91 1.85 1.89 1.91 1.88 0.051 0.9992
6 2.07 2.22 2.14 2.20 2.29 2.18 0.063 0.9776
7 1.43 1.47 1.48 1.42 1.44 1.44 0.024 0.9859
8 2.89 2.99 2.77 2.82 2.83 2.88 0.075 0.9810
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3.2. Haematology

Table 3 reveals the effect of dietary SHLM on haematological indices of broiler chickens at the fourth week of age. SHLM affected (p < 0.05) the heterophil and lymphocyte counts of chickens. The observed difference in heterophil count was between 1% and 10% levels of SHLM. Lymphocyte count was between 5% (44.00%) and 10% (56.00%) in addition to the diet. Other haematological indices evaluated were not significantly (p > 0.05) influenced by levels of SHLM in the diet.

TABLE 3.

Haematological indices of broiler chickens at 4 weeks of age.

Stylosanthes hamata leaf meal
Parameter 0% 1% 5% 10% 15% 20% p Value
Packed cell volume (%) 21.50 ± 3.93 17.50 ± 5.20 13.75 ± 4.39 18.75 ± 3.22 21.75 ± 2.78 20.75 ± 3.77 0.7032
Red blood cell (×1012/L) 1.12 ± 0.30 1.19 ± 0.19 1.52 ± 0.19 0.67 ± 0.11 1.59 ± 0.09 1.65 ± 0.77 0.4130
Haemoglobin (g/dL) 11.07 ± 0.85 7.06 ± 1.98 6.83 ± 2.39 6.98 ± 1.57 7.50 ± 1.022 8.95 ± 1.29 0.4096
White blood cell (×109/L) 2.49 ± 0.97 5.89 ± 1.08 3.80 ± 1.60 3.52 ± 0.97 1.64 ± 0.16 5.140 ± 1.29 0.1169
Basophil (%) 0.00 ± 0.00 0.00 ± 0.00 0.25 ± 0.25 0.50 ± 0.29 0.25 ± 0.25 0.00 ± 0.00 0.3485
Eosinophil (%) 1.00 ± 0.71 1.75 ± 0.63 2.25 ± 0.75 2.00 ± 0.41 1.25 ± 0.48 1.50 ± 0.29 0.6461
Heterophil (%) 46.50 ± 3.52ab 52.00 ± 1.41a 49.00 ± 0.91ab 39.00 ± 2.35b 41.75 ± 2.02ab 44.00 ± 2.74ab 0.0102
Lymphocyte (%) 49.50 ± 3.50ab 43.50 ± 0.96b 44.00 ± 2.68b 56.00 ± 2.74a 55.25 ± 1.97ab 51.75 ± 3.12ab 0.0105
Monocyte (%) 3.00 ± 0.41 2.75 ± 0.48 3.50 ± 0.500 2.50 ± 0.29 2.25 ± 1.32 2.75 ± 0.75 0.8637
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Note: Means within same row having different superscript letters ‘a’ and ‘b’ differs (p < 0.05).

3.3. Plasma triiodothyronine

The effect of SHLM inclusion in the diet on plasma triiodothyronine (T3) concentration of broiler chickens between 4 and 8 weeks of age is presented in Table 4. Dietary inclusion of SHLM significantly (p < 0.05) influenced plasma triiodothyronine concentrations at the sixth week of age. Broiler chickens that received 5% (1.28 ng/mL) and 15% (1.28 ng/mL) SHLM had higher (T3) than those on 1% SHLM treatment (1.07 ng/mL). Others were not different from those on 1%.

TABLE 4.

Plasma triiodothyronine (ng/mL) of broiler chickens fed diet containing Stylosanthes hamata leaf meal between 4 and 8 weeks of age.

S. hamata leaf meal
Age (week) 0% 1% 5% 10% 15% 20% p Value
4 1.09 ± 0.03 1.10 ± 0.022 1.20 ± 0.03 1.11 ± 0.04 1.16 ± 0.04 1.11 ± 0.03 0.7161
5 1.12 ± 0.03 1.14 ± 0.03 1.15 ± 0.03 1.17 ± 0.02 1.17 ± 0.02 1.64 ± 0.30 0.0567
6 1.13 ± 0.07ab 1.07 ± 0.05b 1.28 ± 0.06a 1.11 ± 0.03ab 1.28 ± 0.07a 1.13 ± 0.02ab 0.0399
7 1.23 ± 0.04 1.21 ± 0.08 1.22 ± 0.07 1.14 ± 0.05 1.43 ± 0.10 1.25 ± 0.06 0.1557
8 1.58 ± 0.14 1.28 ± 0.06 1.36 ± 0.08 1.57 ± 0.04 1.50 ± 0.08 1.55 ± 0.07 0.0948
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Note: Means within same row having different superscript letters ‘a’ and ‘b’ differ significantly (p < 0.05).

3.4. Plasma cortisol

Table 5 reveals the effect of SHLM addition to the diet on the plasma cortisol of broilers. There was no significant (p > 0.05) influence of SHLM at the fourth to seventh week of age. However, significant (p < 0.05) variation in the plasma cortisol level of chickens was recorded at the eighth week of age. Chickens on 15% SHLM/100% of basal diet had significantly (p < 0.05) higher cortisol (3.22 ng/mL) concentration compared to 10% (3.13 ng/mL) and 20% (3.16 ng/mL) SHLM/100% treatment groups. Cortisol concentrations of other treatment groups were statistically similar.

TABLE 5.

Plasma cortisol (ng/mL) of broiler chickens fed diet containing Stylosanthes hamata leaf meal.

S. hamata leaf meal
Age (week) 0% 1% 5% 10% 15% 20% p Value
4 3.16 ± 0.03 3.17 ± 0.03 3.15 ± 0.02 3.13 ± 0.034 3.17 ± 0.04 3.13 ± 0.04 0.8048
5 3.18 ± 0.01 3.18 ± 0.02 3.16 ± 0.02 3.17 ± 0.025 3.16 ± 0.03 3.16 ± 0.03 0.4198
6 3.15 ± 0.12 3.21 ± 0.02 3.17 ± 0.04 3.21 ± 0.030 3.21 ± 0.02 3.23 ± 0.02 0.9002
7 3.15 ± 0.01 3.22 ± 0.01 3.20 ± 0.04 3.22 ± 0.024 3.17 ± 0.04 3.22 ± 0.01 0.1948
8 3.19 ± 0.02ab 3.19 ± 0.02ab 3.17 ± 0.01abc 3.13 ± 0.01c 3.22 ± 0.02a 3.16 ± 0.02bc 0.0275
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Note: Means within same row having different superscript letters ‘a’, ‘b’ and ‘c’ differ significantly (p < 0.05).

The effect of SHLM inclusion in the diet on haematological indices of broiler chickens at 8 weeks of age is presented in Table 6. The parameters were not affected by the treatment.

TABLE 6.

Haematological indices of broiler chickens fed diet containing Stylosanthes hamata leaf meal at 8 weeks of age.

S. hamata leaf meal
Parameter 0% 1% 5% 10% 15% 20% p Value
PCV a 33.75 ± 4.40 29.50 ± 9.67 28.75 ± 2.66 29.50 ± 2.33 30.50 ± 3.79 31.25 ± 5.06 0.9869
RBC c 1.70 ± 0.29 2.22 ± 0.22 1.65 ± 0.27 2.20 ± 0.37 2.02 ± 0.32 2.34 ± 0.52 0.6361
HB (g/dL) 11.25 ± 1.90 7.19 ± 1.63 8.65 ± 1.65 21.62 ± 13.07 9.68 ± 1.12 9.63 ± 1.08 0.5055
WBC b 2.09 ± 0.34 2.25 ± 0.16 2.11 ± 0.37 1.77 ± 0.14 3.52 ± 1.85 2.55 ± 0.87 0.7722
Basophil a 0.00 ± 0.00 0.00 ± 0.00 0.00 ± 0.00 0.50 ± 0.29 0.25 ± 0.25 0.00 ± 0.00 0.1637
Eosinophil a 1.50 ± 0.28 1.25 ± 0.48 1.25 ± 0.63 0.75 ± 0.25 1.25 ± 0.63 1.75 ± 0.48 0.7904
Heterophil a 46.00 ± 4.50 44.75 ± 4.53 51.00 ± 3.19 47.00 ± 2.86 48.00 ± 5.40 50.75 ± 1.11 0.8221
Lymphocyte a 50.25 ± 3.88 52.25 ± 3.12 47.00 ± 2.04 49.75 ± 2.72 48.00 ± 4.42 45.25 ± 1.25 0.6612
Monocyte a 2.25 ± 0.48 2.25 ± 0.95 2.25 ± 0.25 2.00 ± 0.41 2.50 ± 0.96 2.25 ± 0.48 0.9972
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Abbreviations: HB, haemoglobin; PCV, packed cell volume; RBC, red blood cells; WBC, white blood cells.

a

%.

b

×109/L.

c

×1012/L.

3.5. Serum creatinine

The effect of SHLM in the diet on the creatinine concentration of broiler chickens is presented in Table 7. Treatment groups, regardless of the age of chickens (week), had similar (p < 0.05) mean plasma creatinine values.

TABLE 7.

Plasma creatinine concentration (mg/dL) of broiler chickens fed diet containing Stylosanthes hamata leaf meal.

S. hamata leaf meal
Age (week) 0% 1% 5% 10% 15% 20% p Value
4 0.35 ± 0.03 0.37 ± 0.03 0.35 ± 0.02 0.38 ± 0.03 0.37 ± 0.02 0.37 ± 0.03 0.8048
5 0.38 ± 0.01 0.41 ± 0.04 0.34 ± 0.03 0.38 ± 0.02 0.41 ± 0.03 0.41 ± 0.04 0.4198
6 0.40 ± 0.06 0.48 ± 0.03 0.33 ± 0.02 0.41 ± 0.027 0.42 ± 0.03 0.46 ± 0.02 0.0883
7 0.54 ± 0.02 0.51 ± 0.08 0.57 ± 0.06 0.61 ± 0.039 0.59 ± 0.02 0.58 ± 0.04 0.6435
8 0.77 ± 0.02 0.73 ± 0.04 0.83 ± 0.06 0.73 ± 0.021 0.74 ± 0.03 0.70 ± 0.03 0.2554
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3.6. Carcass traits

The influence of varying inclusion levels of SHLM on carcass characteristics of 8‐week‐old broiler chickens is presented in Table 8. The results obtained showed that SHLM addition to the basal diet had no significant (p > 0.05) influence on evaluated carcass traits of broiler chickens.

TABLE 8.

Carcass characteristics of broiler chickens fed diet containing Stylosanthes hamata leaf meal.

S. hamata leaf meal
Absolute weight (g) 0% 1% 5% 10% 15% 20% SEM p Value
Live weight (g) 2830.00 2815.0 2835.00 2820.00 2822.50 2825.00 8.297 0.9910
Drumstick (g) 268.43 267.88 281.80 272.70 270.48 273.55 3.758 0.9308
Breast (g) 764.20 749.43 806.35 782.03 725.38 785.13 10.823 0.3329
Thigh (g) 273.55 287.48 309.95 254.25 287.45 253.58 7.131 0.1542
Wing (g) 208.85 212.15 210.35 211.30 205.95 209.63 2.177 0.9818
Whole GIT (g) 101.70 106.20 123.43 111.23 117.03 97.13 4.160 0.5011
Liver (g) 49.08 51.65 48.70 37.50 44.05 40.20 1.740 0.1110
GIT length (cm) 208.00 219.25 209.25 204.25 237.50 187.25 6.218 0.3191
Relative weight (%)
Drumstick 9.49 9.5 9.94 9.67 9.59 9.68 0.138 0.9619
Breast 26.98 26.63 28.46 27.73 25.70 27.80 0.373 0.3457
GIT 3.60 3.77 4.36 3.95 4.16 3.44 0.153 0.5608
Shank 3.13 3.14 3.29 3.21 3.09 3.23 0.043 0.8244
Thigh 9.66 10.22 10.94 9.01 10.20 8.98 0.258 0.1841
Wing 7.38 7.54 7.43 7.49 7.30 7.42 0.082 0.9821
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Abbreviation: GIT, Gastrointestinal tract.

4. DISCUSSION

This study aimed to evaluate the influence of dietary SHLM incorporation in the diet of broilers to establish appropriate levels the birds could tolerate without adverse effects on their productivity. Our findings demonstrated that different levels of SHLM inclusion did not influence the growth performance indices of broilers. The performance parameters were not significantly different irrespective of inclusion levels of SHLM. This suggests that the different inclusion levels were able to compensate for the reduction in the amount of basal diet. Besides the protein content, forage legumes have been reported to contain more minerals and vitamins than most cereals (Aarti et al., 2005; Lajide et al., 2008), which can play the role of industrial premix supplementation (Leterme et al., 2006). It has been shown that broiler chickens may recover from growth limitations caused by methionine shortage by consuming forage plants (Moritz et al., 2005). The similarity in weight gains of broilers in the present trial agrees with the result of Changjun et al. (2004), who demonstrated that the inclusion levels of different Stylosanthes mixes (Stylosanthes scabra, Stylosanthes guianensis and S. hamata) had no significant influence on growth performance. The comparable growth performance in the present study suggests that the inclusion of SHLM up to 20% had no adverse effect on feed intake and weight gain. This supports the result of Gupta et al. (1992), who indicated that stylo might be fed to chickens. More so, our findings are in agreement with Walker and Gordon (2003), who demonstrated that pasture is an essential source of vitamins, protein and energy, which decreased the intake of conventional diets by up to 10%. The present result also agrees with Fanatico (1998), who indicated that the intake of forage plants could reduce the consumption of conventional diets by up to 30%. Our findings in this study are in partial contrast with the earlier reports of Ponte et al. (2008), who recorded improved body weights in broilers with access to pasture and also Oke et al. (2015), who indicated that FCR was enhanced in the hens’ exposed legume intake on the free runs than those raised in the grass pasture. The authors did not, however, vary the quantity of Stylosanthes the birds had access to. The similarity in the growth performance across the treatment groups in the current study corroborates the findings of Horsted et al. (2007), who showed that pasture consumption by birds might act as a form of nutritional insurance, thereby helping poultry farmers to save the cost of production. The ability of the broiler chickens to utilize the SHLM in the present study up to 20% affirms the reports of Buchanan et al. (2007) and Spencer (2013) that poultry can utilize most of the amino acids in legumes.

The feed intake was similar to diets containing SHLM compared to the control diet. The chemical composition and type of dietary fibre are known to influence voluntary intake in monogastric animals (Martens et al., 2012). The similarity in the feed intake of the birds in the present study could result from the tolerable content of anti‐nutritional factors present in legume foliage due to the effect of foliage processing (sun drying). Heat treatments, including sun drying, have been reported to reduce heat‐labile anti‐nutritional factors (Borin et al., 2005; Bui‐Huy et al., 2000).

Forage legumes are reliable minerals, vitamins and protein sources for monogastric animals (Norton, 1994). Green legume forages generally have been reported to have acceptable amino acids. Therefore, the forage's amino acid composition is highly important when used as a monogastric protein source (Phuc & Lindberg, 2001). The increase in the inclusion of SHLM in the diet may suggest that dietary fibre increase did not also affect carcass traits in the present study. This indicates proper fibre utilization. Ouhayoun (1998) also stated that a significant increase in dietary fibre content of diets only sometimes leads to modification in growth rate and slaughter yield.

Biochemical and haematological indices are reliable biomarkers of the physiological status of animals. They are generally used to evaluate the health condition of animals (Khan & Zafar, 2005). The inclusion of SHLM in the diet of broilers did not affect most of the haematological parameters except neutrophil and lymphocyte, which were significantly different. The similarity in the PCV, RBC and haemoglobin concentration suggests protein adequacy of the diet. The similarity in the growth performance of the birds across the treatment groups in the study can be explained by the comparable haematological and biochemical parameters. The non‐significant difference in WBC count obtained indicates the safety of SHLM inclusion in the diet. This also serves as an indication that the diets did not compromise the immune status of the chickens. In this study, the plasma cortisol was not significantly influenced by S. hamata (SHLM) inclusion up to the seventh week of the trial; however, a significant difference was observed in the eighth week of the experiment. There was, however, no consistency in the trend of hormonal concentration. Interestingly, birds fed a diet containing SHLM at 10% had a lower concentration of cortisol at week 8 than those in the control group. This may suggest that the antioxidant level of the meal was optimal to combat oxidative stress at this dose. Increased plasma cortisol is an indication of stress conditions that may arise due to environmental conditions, nutritional imbalances and digestive disorders (Sasaki & Weekes, 1986; Hashizume et al., 1994). Reduced cortisol levels are connected with improved immunity (Kegley & Spears, 1995) and increased antibody production (Gross, 1992).

Triiodothyronine (T3) is a metabolic hormone which influences various physiological events, including heart rate, body temperature, metabolism, growth and development (Bowen, 2010). There was no difference in the plasma triiodothyronine of the birds except at week 6 in the present study, suggesting that the incorporation of SHLM did not impair the thyroid activities of the birds. The creatinine levels of the broilers across the treatments in this study were within the normal range of 0.1–0.4 mg/dL documented by Merck Manual (2012) up to the sixth week of age. Slightly higher levels observed at the later age of the birds are in agreement with the observation of Owosibo et al. (2013). The similarity in the serum creatinine of the chickens in the present study implies there was no detrimental effect of the diet on the proper functioning of the kidney and may also indicate the absence of muscle wasting. Any increases above the expected range of creatinine can be considered an indication of renal impairment (Debra‐Manzella, 2018). However, the results of the present study were within the normal range for broiler chickens.

The similarity in the serum creatinine also explains the lack of difference in the performance parameters of the broilers.

The inclusion of SHLM did affect the carcass characteristics of the chickens in the present study. Similar to our results, Hien et al. (2017) also reported that there was no significant effect of forage inclusion in the diet of broilers on the carcass weight, liver weight and abdominal fat weight when compared with the control. Changjun et al. (2004) also reported similarity in carcass yield of broiler chickens fed a diet containing Stylosanthes leaf meal at 6% inclusion levels for starting and finishing broilers in China. This similarity could result from nutrient sufficiency of the diet and hence adequate nutrient availability, which led to a comparable performance across the treatment, irrespective of inclusion levels of SHLM.

This study has demonstrated that the performance indices of broiler chickens were not significantly altered by SHLM by up to 20%. The metabolic hormone of the birds was not adversely affected by the diets. This study also showed that a 10% inclusion of SHLM in the eighth week significantly reduced plasma cortisol concentration. Moreover, the carcass traits of broilers were not significantly affected by SHLM inclusion by up to 20%. To reduce the cost of production, poultry farmers could incorporate SHLM in the diets of the birds.

AUTHOR CONTRIBUTIONS

Data curation; formal analysis; investigation; methodology; resources; software; validation; visualization; writing – original draft; writing – review and editing: Adewale E. Adejuyigbe. Investigation; project administration; supervision; writing – original draft; writing – review and editing: Olajide M. Sogunle. Conceptualization; data curation; formal analysis; investigation; methodology; project administration; resources; supervision; validation; visualization; writing – original draft; writing – review and editing: Okanlawon M. Onagbesan. Conceptualization; data curation; formal analysis; funding acquisition; investigation; methodology; project administration; resources; supervision; validation; visualization; writing – original draft; writing – review and editing: Oyegunle E. Oke.

FUNDING INFORMATION

No funding was received for this study.

ETHICAL STATEMENT

The Animal Experimental Board of the Department of Animal Physiology, College of Animal Science and Livestock Production, Federal University of Agriculture, Abeokuta Nigeria, authorized the experiment, and the Nigeria Institute of Animal Science (NIAS) standard for Animal Research was followed. Animal cruelty and unnecessary suffering were avoided.

PEER REVIEW

The peer review history for this article is available at https://publons.com/publon/10.1002/vms3.1237.

Adejuyigbe, A. E. , Sogunle, O. M. , Onagbesan, O. M. , & Oke, O. E. (2023). Growth performance and physiological responses of broilers fed Stylosanthes hamata leaf meal in a hot tropical environment. Veterinary Medicine and Science, 9, 2150–2159. 10.1002/vms3.1237

DATA AVAILABILITY STATEMENT

The data that support the findings of this study are available on request from the corresponding author. The data are not publicly available due to privacy or ethical restrictions.

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Associated Data

This section collects any data citations, data availability statements, or supplementary materials included in this article.

Data Availability Statement

The data that support the findings of this study are available on request from the corresponding author. The data are not publicly available due to privacy or ethical restrictions.

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